This invention relates in general to the construction of shaft seals and in particular to a new and useful hydrostatic and hydrodynamic shaft seal for a rotating shaft.
The invention relates particularly to a hydrostatic or hydrodynamic shaft seal, including a ring revolving with the shaft and an axially movable static ring which is sealed from the housing by two O-rings, and forms, with the revolving ring, radial seal gaps through which an incompressible fluid flows and stabilizes the seal gap. Such shaft seals for compressors and other machines must seal the process spaces in the zone of the shaft passage through the housing from the atmosphere and insure that only very little stopping medium gets into the process space.
Such seals include a ring revolving with the shaft and a static seal ring which is pressed against the end face of the revolving ring and with it forms the seal gap. With the hydrostatic principle for supplying stopping medium into the seal gap, the static seal ring has three or more throttle elements, which lead into as many pockets concentrically distributed over the circumference. From these pockets the stopping medium flows to both sides through the seal gap outwardly into the process space and inwardly into the atmosphere. thus, independently of the stopping medium pressure, a seal gap may occur which, during operation, avoids metallic contact of the two rings and stabilizes itself by the interaction of stopping medium throttle throughput and gap throughput.
Due to the automatic stabilization of the seal gap, minimal gaps and hence minimal stopping medium throughputs can be achieved, which, in most known seal designs, are very difficult to realize, for manufacturing and physical reasons, without getting to the limits of operational safety.
The samll quantities of stopping medium of known hydrostatic and hydrodynamic seals are, however, unable to remove the friction heat created in the gap during operation. The seal rings must be cooled from the outside if overheating in the gap is to be avoided. But thereby the usability of these known seal types is limited to low circumferential speeds in the seal area.
It is the object of the invention to substantially increase the safe speed range in a hydrostatic or hydrodynamic shaft seal.
The invention solves this problem in the manner as stated in the characteristics of the patent claims. The seal according to the invention has an intensive internal cooling, which permits using it also in speed ranges at which turbocompressors and other high-speed machines are operated.
Accordingly it is an object of the invention to provide an improved seal for a rotating shaft which includes a revolving ring revolving with the shaft and a static ring which is movable only axially in respect to the shaft and forms radial seal gaps with the revolving ring and which includes a pair of axially spaced O-rings sealing the static ring with the housing and permitting its axial mobility, the static ring with the revolving ring form radial gaps for the flow of an incompressible fluid therethrough having a flowthrough valve passage into which a valve ring member extends so as to control the pressure on the fluid which flows through the cavity of the static ring and for this purpose the valve ring is biased by spring.
A further object of the invention is to provide a shaft seal which is simple in design, rugged in construction and economical to manufacture.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.